Deep levels produced by triplet vacancy-impurity complexes in GaP

A theory of the deep energy levels produced by triplet vacancy-impurity complexes in GaP is outlined. The major chemical trends in the deep levels of a1, b1, and b2 symmetry are predicted for 56 such complexes in this material. These calculations show that a triplet vacancy-impurity complex can produce deep levels at energies where neither the corresponding vacancy-impurity pair nor the isolated impurity produce any.